(a) Technical Field
The present disclosure relates to a method for producing synthetic leather. More particularly, it relates to a method for producing synthetic leather, which is suitable for vehicle interior materials (such as seat covers, door trim sheets, etc.) and has improved air permeability, which is similar to that of genuine leather. Moreover, the synthetic leather produced by the present invention has increased hydrolysis resistance and chemical resistance, which genuine leather does not have, increased flame retardancy and, at the same time, has improved adhesion between a fabric and a film along with improved film texture.
(b) Background Art
Generally, synthetic leather is a fabric produced by forming a film with a synthetic resin such as polyvinyl alcohol (PVA) or polyurethane (PU) on a release paper (RP), on which a leather pattern or other predetermined pattern is embossed, and bonding the resulting film to a woven fabric, knitted fabric, or nonwoven fabric using an adhesive. The methods for producing synthetic leather generally include a dry method and a wet method.
According to the dry method, a film is formed on the surface of a release paper using a polyurethane solution or solvent-based polyurethane (PU) resin (prepared by dissolving polyurethane in toluene and methyl ethyl ketone (MEK). That is, a solvent-based polyurethane solution, for example, is coated on a release paper and dried to form a film on the release paper. Then, the resulting release paper is bonded to a fabric coated with an adhesive and dried, and the release paper is removed from the film, thereby forming the final film on the fabric.
The wet method, utilizes a resin, such as solvent-based PU resin, capable of forming a film is padded onto the surface of a fabric or onto the entire fabric. Alternatively, a PU resin may be coated on the surface of a fabric (such as a woven fabric, knitted fabric, or nonwoven fabric) embedded in a synthetic resin by gravure coating, for example, thus forming a film. Moreover, a wet/dry method, in which a release paper is attached to the thus formed film, may be used.
However, the synthetic leather produced by the above-described conventional methods, in which the thus formed film is bonded to the surface of the fabric by an adhesive, has no air permeability similar to that of genuine leather, since the surface of the fabric is completely covered by the film, as shown in the images of FIGS. 6A, 6B, 7A and 7B.
Moreover, the use of adhesives causes contaminants such as volatile organic compounds (VOCs) and odors, not to mention that the use of solvents (such as toluene and MEK), which may be harmful to the human body, is not environmentally friendly.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.